KR101140165B1 - Compensating Circuit for Vcom and It's Method - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a common voltage of a liquid crystal display device, and more particularly, to a common voltage compensation circuit and a compensation method of a liquid crystal display device that minimizes distortion of a common voltage to increase display efficiency.

Conventionally, in the common voltage swing drive type common voltage generation circuit, a coupling phenomenon occurs due to a parasitic cap formed at an intersection (overlap region) between a data line and a common line as the data voltage is periodically inverted in polarity And the common voltage is distorted by such coupling, thereby causing a horizontal crosstalk phenomenon.

In order to solve such a problem, a common voltage compensation circuit according to the present invention measures a coupling signal in first and second dummy common wirings formed on the upper or lower end of a panel, and feeds back the coupled signal to the common voltage compensation circuit, The common voltage is inverted and amplified to improve the distortion of the common voltage.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a common voltage compensation circuit,

1 is an equivalent circuit diagram showing a unit pixel of a general liquid crystal display device.

2A and 2B are diagrams showing conventional first and second common voltage generating circuits, respectively.

3 is a block diagram of a configuration of a common voltage compensation circuit for common voltage swing according to the present invention.

Figures 4A and 4B illustrate first and second compensation circuits, respectively, according to the present invention.

5 is a view for explaining a coupling signal measuring unit according to the present invention.

Description of the Related Art [0002]

310: power supply distributor 320: inverting amplifier

330: compensating unit 340: coupling measuring unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a common voltage of a liquid crystal display device, and more particularly, to a common voltage compensation circuit and a compensation method of a liquid crystal display device that minimizes distortion of a common voltage to increase display efficiency.

In general, a liquid crystal display device has a structure in which first and second substrates, each having a pixel electrode as a first electric field generating electrode and a common electrode as a second electric field generating electrode, are adhered to each other with a predetermined spacing therebetween, Layer is interposed therebetween.

2. Description of the Related Art A liquid crystal display (LCD) displays a desired image by driving electric field liquid crystal molecules formed between a pixel electrode and a common electrode. In recent years, an active matrix liquid crystal display -LCD) is generally used because of its excellent resolution and video realization capability.

1 is an equivalent circuit diagram showing a unit pixel of a general liquid crystal display device.

The unit pixel of the liquid crystal display device includes a gate wiring GL and a data wiring DL formed in the direction in which the unit pixel intersects and a thin film transistor T formed at the intersection of the two wirings GL and DL, A liquid crystal capacitor LC and a storage capacitor Cst connected in parallel with the thin film transistor T. The other side of the liquid crystal capacitor LC is connected to the common line Vcom and the other side of the storage capacitor Cst And is connected to the gate wiring GL.

The operation of the liquid crystal display device will be briefly described. When the thin film transistor T is turned on by the driving signal applied to the gate line GL, the data signal (pixel voltage) (Not shown), and an electric field is generated by a voltage difference between the pixel electrode (not shown) and the common electrode (not shown), more precisely, a voltage difference between the pixel voltage and the common voltage.

The liquid crystal molecules are driven by such an electric field to control the amount of light transmitted, thereby displaying a desired image.

In this case, if a DC voltage is applied to the liquid crystal for a long time, characteristic deterioration occurs. Therefore, in order to prevent deterioration of characteristics, a polarity inversion driving method is used to periodically change the polarity of the applied voltage, and a polarity inversion driving method A voltage swing (Vcom swing) driving method is used.

The common voltage swing driving method is a method of driving the polarities of the pixels to be polar inversion in units of horizontal pixel columns. More specifically, the common voltage swing driving method includes first and second common voltages, The second common voltage is applied, and the polarities of the first and second common voltages are inverted every one vertical period, and their polarities are opposite to each other.

That is, when the first common voltage is a positive polarity, the second common voltage is negative, and the polarity is inverted in the next frame (after one vertical period) so that the first common voltage is negative (-) polarity , And the second common voltage is positive (+) polarity.

FIGS. 2A and 2B are diagrams showing a conventional first and second common voltage generating circuits, respectively.

2A, the first common voltage generating circuit includes a power dividing unit 210 and an inverting amplifying unit 220. The power dividing unit 210 is connected between the power voltage terminal Vcc and the ground And a first variable resistor (VR1) which is formed in series with the first variable resistor (VR1), and distributes the power supply voltage by adjusting the first variable resistor (VR1).

The inverting amplifier unit 220 includes an operational amplifier OP having a noninverting input terminal (+), an inverting input terminal (-) and an output terminal. The voltage divider 210 divides the voltage divided by the noninverting input terminal (+ And receives the first polarity control signal for inverting the polarity at one vertical period through the inverting input terminal (-), receives the first common voltage inverted and amplified at the period of the first polarity control signal (one vertical period) Output.

At this time, the output terminal of the operational amplifier OP is connected to the output terminal of the operational amplifier OP as a signal of the common base terminal, and the first and second transistors And an analog buffer 222 composed of transistors TR1 and TR2 are formed.

Also, a first capacitor C1 and a second variable resistor VR2 are formed in parallel between the feedback line, that is, the output of the analog buffer 222 and the inverting input terminal (-). The polarity control signal input terminal and the inverting input terminal - >).

FIG. 2B is a diagram showing a second common voltage generator circuit of the conventional common voltage swing drive system, and the second common voltage generator circuit has the same configuration as that of the first common voltage generator circuit, 1 common voltage generation circuit.

The second common voltage generating circuit receives the second polarity control signal at the inverting input terminal (-) of the operational amplifier OP, the second polarity control signal is inverted every one vertical period, and the first polarity control signal and the polarity This is the opposite.

Accordingly, the second common voltage having the same polarity as the first common voltage and the opposite polarity of the polarity is outputted.

In this manner, the first and second common voltage generating circuits are inverted in polarity every one vertical period, and first and second common voltages having opposite polarities (phase difference of 180 degrees) are generated and applied to the panel.

On the other hand, the first and second common voltages must maintain the DC voltage for one vertical period (one frame). As the data signal (voltage) is periodically inverted, data lines (not shown), common lines The coupling phenomenon occurs due to the parasitic cap formed at the intersection (overlap region)

As a result, the common voltage supplied to the inside of the panel is distorted as much as the coupling signal, and a horizontal crosstalk phenomenon occurs due to the distortion of the common voltage.

In order to solve the problem of the common voltage swing drive method, the common voltage compensation circuit according to the present invention measures the coupling signal from the dummy common wiring at the upper or lower end of the panel, Thereby improving the distortion caused by the signal and supplying a stable common voltage to the panel.

To achieve the above object, according to the present invention, there is provided a common voltage compensation circuit comprising: a coupling measurement unit for measuring a coupling signal generated in first and second common voltages according to a polarity inversion of a data signal in a panel; And a first non-compensation reference signal receiving the first polarity control signal and inverting and amplifying the first non-compensation reference signal, wherein the first non-compensation reference signal is supplied with the reference voltage, And a second common voltage generator for receiving a coupling signal generated at the first common voltage from the coupling measuring unit and receiving the coupling signal at the first common voltage corresponding to the coupling signal, A first compensation circuit including a compensation section for inverting and amplifying the common voltage; And a second non-compensated reference signal which is inversely amplified by receiving a second polarity control signal and receiving a voltage that is distributed from the power distributor as a reference voltage and receives an output of the reference voltage, A second common voltage generating unit for receiving a coupling signal generated from the coupling measuring unit to generate a second common voltage and outputting a second signal corresponding to the coupling signal, And a second compensation circuit including a compensation unit for inverting and amplifying the common voltage.

At this time, the first and second polarity control signals are polar inversed every one vertical period, and the polarities of the first and second polarity control signals are opposite to each other.

The coupling measurement unit measures a coupling signal of the first and second common voltages in the first and second dummy common lines formed at the upper end of the panel or the first and second dummy common lines formed at the lower end of the panel do.

The wiring for measuring the coupling signal is electrically connected to the gate PCB formed on the left side of the panel to feed back the measured coupling signal.

The first and second common voltages compensated by the first and second common voltage compensation circuits are applied to various external connection positions connected to the common wiring formed on the panel.

The power distributor comprises a first resistor and a first variable resistor connected in series between a power supply voltage terminal and ground.

Wherein the inverting amplifier comprises a first operational amplifier having an inverting input terminal, a noninverting input terminal and an output terminal, a first capacitor and a second variable resistor formed in parallel between the output terminal and the inverting input terminal of the first operational amplifier, And a second resistor connected to the non-inverting input terminal.

The first operational amplifier receives the voltage divided from the power distributing unit into the non-inverting input terminal and receives the polarity control signal from the inverting input terminal.

Wherein the compensation unit comprises a second operational amplifier having an inverting input terminal, a noninverting input terminal and an output terminal, an analog buffer is formed at an output terminal of the second operational amplifier, and an output of the analog buffer and an inversion A third resistor formed in parallel between the input terminal and the third resistor, a fourth resistor connected to the inverting input terminal, a third resistor connected to the non-inverting input terminal, And a fifth resistor is formed between the front ends of the fourth resistors.

The second operational amplifier receives the output of the first operational amplifier as the reference voltage, and receives the coupling signal measured by the coupling measuring unit at the non-inverting input terminal.

The analog buffer is constituted by first and second transistors which are formed in series and whose both ends are connected to a power supply voltage terminal and a ground, with the output of the second operational amplifier being a signal of a common base terminal.

According to another aspect of the present invention, there is provided a method of compensating for common voltage, comprising: measuring a coupling signal of a first common voltage and a second common voltage through a coupling measurement unit; Dividing the power supply voltage in each of the power distributing units of the first and second compensating circuits, and inputting the divided power voltage as a reference voltage to the respective inverting amplifying units; Receiving first and second polarity control signals from the respective inverting amplifying units and outputting first and second non-compensated reference signals inverted and amplified by feedback of the output; The first and second non-compensated reference signals are received as reference voltages and the outputs are fed back, and the coupling signals of the first and second common voltages are respectively received from the coupling measurement unit, Correspondingly inverting and amplifying the first and second common voltages to compensate for the first and second common voltages; And applying the compensated first and second common voltages to a plurality of external connection positions connected to a common wiring formed on the panel.

At this time, the first and second polarity control signals are polar inversed every one vertical period, and the polarities of the first and second polarity control signals are opposite to each other.

The coupling measuring unit measures the coupling signal in the first and second dummy common wiring formed on the upper end of the panel or the first and second dummy common wiring formed in the lower end of the panel, respectively.

The coupling signal is electrically connected to the gate PCB formed on the left side of the panel, and the feedback signal is fed back to the compensation unit of the compensation circuit.

In order to achieve the above object, a liquid crystal display according to the present invention is formed in a direction crossing a plurality of gates and data lines defining a pixel region, and a thin film transistor, which is a switching element, is formed at an intersection of the gate and the data line And a plurality of common wirings formed in parallel with the gate wirings and in which first and second common voltages are alternately applied are formed in parallel with the thin film transistors to form liquid crystal capacitors and storage capacitors, A panel formed; And a coupling signal generated in the first and second common voltages in accordance with the polarity inversion of the data signal in the panel is supplied to the first and second dummy common lines formed on the upper portion of the panel, And a second dummy common wiring, a power distributing unit for distributing a power supply voltage, a voltage dividing unit for receiving a voltage distributed from the power distributing unit as a reference voltage, receiving an output of the voltage dividing unit, An inversion amplifier unit for receiving the inverted amplified non-compensated reference signal, an inversion amplifier unit for receiving the output of the inverting amplifier unit as a reference voltage, receiving an output of the inverting amplifier unit as a reference voltage, receiving the coupling signal measured by the coupling measuring unit, And a compensating circuit for inverting and amplifying the first and second compensating circuits.

In this case, the polarity control signals input to the first and second compensation circuits are first and second polarity control signals which are polarity inversed every one vertical period and have opposite polarities.

The coupling signals input to the first and second compensation circuits are coupling signals generated at the first and second common voltages, respectively.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a configuration block diagram of a common voltage compensation circuit for common voltage swing according to the present invention.

The common voltage swing drive system is driven by alternately configuring the first and second common voltages, and the common voltage compensation circuit includes first and second compensation circuits for compensating the first and second common voltages, Since the configurations of the first and second compensation circuits are the same, for convenience of explanation, the first and second compensation circuits are not described separately.

As shown in the figure, the common voltage compensation circuit according to the present invention includes: a power distributor 310 for dividing a power supply voltage and supplying the divided voltage to the inverting amplifier 320 as a reference voltage; An inverting amplifier 320 for receiving a polarity control signal for inverting an output signal (common voltage) every frame (one vertical period), and outputting a non-compensated reference signal; A coupling measuring unit 340 for measuring a coupling signal generated in the common wiring by a parasitic cap between the wiring and the common wiring, and a coupling measuring unit 340 for receiving a non-compensation reference signal from the inverting amplifying unit 320 as a reference voltage, And a compensation unit 330 receiving the feedback signal and compensating the common voltage and outputting the coupled signal.

In this case, the first and second polarity control signals are input to the first and second compensation circuits, respectively, and the first and second polarity signals are polar inversed every one vertical period, and the polarities of the first and second polarity signals are opposite to each other.

Further, the coupling measuring unit 340 may include a coupling measuring unit 340 for measuring the coupling of the first and second dummy common wirings formed on the upper end of the panel or the first and second dummy common wirings formed on the lower end of the panel, And the first and second dummy common wirings are defined as wirings which are formed in the non-pixel area of the panel and are not used for liquid crystal driving but are applied with the first and second common voltages, respectively.

Hereinafter, a configuration of a common voltage compensation circuit according to the present invention will be described in detail with reference to the accompanying drawings.

Figures 4A and 4B are diagrams illustrating first and second compensation circuits, respectively, in accordance with the present invention.

4A, the first compensation circuit according to the present invention includes a power distributor 310, an inverting amplifier 320, a compensator 330, and a coupling measurement unit (not shown) The distribution unit 310 includes a first resistor R1 and a first variable resistor VR1 that are connected in series between a power supply voltage terminal Vcc and ground and adjusts the size of the first variable resistor VR1, To a voltage of a desired potential.

The inverting amplifier 320 is composed of a first operational amplifier OP1 having an inverting input terminal (-), a noninverting input terminal (+) and an output terminal. The voltage divider 310 divides the voltage distributed from the power dividing unit 310 into a non- +), Receives the output of the first operational amplifier OP1, receives the first polarity control signal CS1 through the inverting input terminal (-), and outputs the inverted amplified first non-compensated reference signal (Vb1).

At this time, a first capacitor C1 and a second variable resistor VR2 are formed in parallel between the feedback line of the first operational amplifier OP1, that is, between the output terminal and the inverting input terminal (-), The second resistor R2 is formed between the inverting input terminal and the inverting input terminal and the gain of the first operational amplifier OP1 is determined by the second resistor R2 and the second variable resistor VR2 , The magnitude of the second variable resistor (VR2) is adjusted to determine the degree of amplification of the output signal.

On the other hand, the first polarity control signal CS1 is a signal whose polarity is inverted every one vertical period, and the output first non-compensation reference signal Vb1 is polarized in one vertical period in synchronization with the first polarity control signal CS1 Is reversed.

The coupling measuring unit measures the coupling signal (voltage) with the data line in the common wiring formed on the panel, not shown, and feeds it back to the coupling signal input terminal, that is, to the compensating unit, and the first and second compensating circuits 4B) is measured by first and second dummy common lines (not shown) formed on the top of the panel or first and second dummy common lines (not shown) formed on the bottom of the panel.

The compensation unit 330 includes a second operational amplifier OP2 having an inverting input terminal (-), a noninverting input terminal (+) and an output terminal, and outputs the output of the inverting amplifying unit 320 as a non- Receives a coupling signal measured by a panel from a coupling measurement unit (not shown), receives the output of the coupling signal, and supplies the compensated first common voltage Vcom1 to the panel.

At this time, the output of the second operational amplifier OP2 is connected to the power supply voltage terminal Vcc and the ground through the output of the second operational amplifier OP2 as a signal of the common base terminal, 1 and the second transistors TR1 and TR2 are formed.

In addition, a second capacitor C2 and a third variable resistor VR3 are formed in parallel between the feedback line of the second operational amplifier OP2, that is, the output terminal and the inverting input terminal (-), A fourth resistor R4 is formed between the inverting input terminal (-) and a third resistor R3 is formed at the non-inverting input terminal (+) receiving the output of the inverting amplifier 320, A fifth resistor (R5) is formed between the input terminal and the output terminal of the inverting amplifier (320).

On the other hand, since the gain of the second operational amplifier OP2 is determined by the fourth resistor R4 and the third variable resistor VR3, the magnitude of the third variable resistor VR3 is adjusted to determine the degree of compensation do.

4B is a diagram illustrating a second compensation circuit. As shown in the figure, the second common voltage compensation circuit includes a power distributor 310, an inverting amplifier 320, a compensator 330, 4A). Since the circuit configuration is the same as that of the first compensation circuit (FIG. 4A), differences from the first compensation circuit (FIG. 4A) will be mainly described.

4B) receives the second polarity control signal CS2 at the inverting input terminal (-) of the first operational amplifier OP1 and precisely receives the second polarity control signal CS2, And the second polarity control signal CS2 is polarity inversed every one vertical period and has a polarity opposite to that of the first polarity control signal CS1.

Therefore, the second non-compensated reference signal Vb2 inverted and amplified is polarized inversion every one vertical period, and has a polarity opposite to that of the first non-compensated reference signal Vb1 (phase difference is 180).

The compensation unit 330 of the second compensation circuit, specifically, the second operational amplifier OP2 receives the second non-compensation reference signal Vb2 as a reference voltage and receives the coupling signal at the inverting input terminal - 2 common voltage (Vcom2) to be supplied to the panel.

Meanwhile, as described above, the coupling signals supplied to the compensation unit 330 of the first and second compensation circuits (FIGS. 4A and 4B) are respectively connected to the first and second dummy common lines And the coupling measuring unit will be described in detail with reference to the drawings.

5 is a view for explaining a coupling signal measuring unit according to the present invention.

As shown in the figure, the common voltage swing drive type first and second common wirings 510 and 520 are alternately arranged, and the first and second compensation circuits (FIGS. 4A and 4B) The coupling signal fed back to the compensating unit 330 of FIG. 4 is applied to the first and second dummy common wirings 512 and 514 formed at the upper end of the panel or the first and second dummy common wirings 512 And 514, and the first and second dummy common wirings 512 and 514 are formed in the upper and lower portions of the pixel region P, that is, in the non-pixel region, and are not used for liquid crystal driving, Are defined as common wirings 510 and 520 to which two common voltages Vcom1 and Vcom2 are applied.

At this time, the first and second dummy common wirings 512 and 514 formed at the top of the panel most strongly exhibit a coupling phenomenon with the data wirings, so that the first and second dummy common wirings 512 and 514 formed at the top of the panel, A method of measuring a coupling signal is most preferable.

Thus, the coupling signal measured at the dummy common lines 512 and 514 at the top or bottom of the panel is electrically connected to the gate PCB 550 formed on the left side of the panel and supplied to the compensation circuit (Figs. 4A and 4B) .

The common voltage is generally input to the four corners of the panel. In order to stably supply the common voltage, in addition to the four corners, the wiring and the gate PCB, to which the first and second common voltages are applied, The first and second additional wirings 516 and 526 are formed to apply the compensated common voltages Vcom1 and Vcom2 or the first and second additional wirings 516 and 526 to apply the coupling signal It can also be measured.

The operation of the common voltage compensation circuit for common voltage swing according to the present invention is as follows.

The common voltage compensation circuit according to the present invention is divided into first and second compensation circuits (Figs. 4A and 4B). The first and second common voltage compensation circuits (Figs. 4A and 4B) The two common voltages Vcom1 and Vcom2 are applied to the first and second common wirings 510 and 520, that is, the odd and even common wiring lines 510 and 520, respectively, The polarity is reversed.

In this case, the first and second compensation circuits (FIGS. 4A and 4B) have the same configuration and operation, the polarities of the polarity control signals are opposite to each other, and the feedback signal is supplied to the first and second dummy common lines 512, and 514, respectively. Therefore, the first and second common voltage compensation circuits (FIGS. 4A and 4B) will not be described separately for convenience of explanation.

The common voltage compensation circuit (FIG. 4) receives the power supply voltage and distributes it to the power supply distribution unit 310. The distributed power supply voltage is supplied to the inverting amplification unit 320, Is input to the non-inverting input terminal (+) as a reference voltage to the operational amplifier OP1.

The inverting amplifier 320 receives the voltage distributed from the power distributing unit 310 as a reference voltage and receives the output of the inverting amplifier 312. The inverting amplifier 320 receives the polarity control signal through the inverting input terminal Compensated reference signal and supplies it as a reference voltage to the compensating unit 330, and more precisely, the second operational amplifier OP2 constituting the compensating unit 330. [

The coupling measuring unit 340 measures the polarity of the data signal in the first and second dummy common wirings 512 and 514 formed at the upper end of the panel or the first and second dummy common wirings 512 and 514 formed at the lower end of the panel And measures the coupling signal according to the inversion, and feeds the coupling signal thus measured to the compensation unit 330, more precisely, the inverting input terminal (-) of the second operational amplifier OP2.

The compensation unit 330 receives the non-compensation reference signal inverted and amplified by the inverting amplifier 320 at a level of the level for driving the liquid crystal as a reference voltage through the non-inverting input terminal (+), and outputs the analog buffer 332 The coarse output signal is fed back and the coupling signal measured by the coupling measuring unit 340 is input through the inverting input terminal (-) and is inverted amplified to correspond to the coupling signal to compensate the common voltage Vcom.

At this time, it is preferable to configure the degree of compensation of the common voltage Vcom, which is inversely amplified in consideration of the loss (reduction of the potential) due to the characteristics of the circuit elements, to be larger than the coupling signal.

On the other hand, in the above-described operation of the common voltage compensation circuit, the polarity control signals applied to the first and second compensation circuits (Figs. 4A and 4B) are the first and second polarity control signals CS1 and CS2, Are inverted every one vertical period, and their polarities are opposite to each other (phase difference is 180 DEG).

The coupling signals input to the first and second compensation circuits (FIGS. 4A and 4B) are respectively connected to the first and second dummy common wirings 512 and 514 formed at the upper end of the panel or the first and second dummy common wirings 512 and 514 formed at the lower end of the panel. And the second dummy common wirings 512 and 514, respectively.

As described above, the common voltage compensation circuit according to the present invention, more specifically, the first and second compensation circuits (FIGS. 4A and 4B) includes first and second dummy common lines 512 And 514, respectively, and receives the feedback signals. The common voltage is inverted and amplified corresponding to the feedback coupling signal,

The parasitic cap formed between the data wiring and the common wiring compensates for the distortion of the common voltage due to coupling which is a tuning phenomenon caused by polarity inversion of the data signal.

As a result, the horizontal crosstalk caused by the distortion of the conventional common voltage is prevented, and the image quality is improved.

The present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention.

As described above, the common voltage compensation circuit according to the present invention includes the first and second compensation circuits, and measures coupling signals in the first and second dummy common wirings formed at the upper or lower end of the panel, 2 compensating circuit, and compensates the signal by inverting and amplifying the common voltage corresponding to the coupling signal, thereby preventing the horizontal crosstalk caused by the distortion of the common voltage and improving the image quality.

Claims (18)

A common voltage compensation circuit for compensating for a coupling signal induced in a common wiring in accordance with a polarity inversion of the data signal in a panel to which a first common signal and a second common signal of opposite polarity are applied, A coupling measuring unit for measuring a coupling signal generated in the first and second common voltages, respectively, in accordance with polarity inversion of the data signal in the panel; And a first non-compensation reference signal receiving the first polarity control signal and inverting and amplifying the first non-compensation reference signal, wherein the first non-compensation reference signal is supplied with the reference voltage, And a second common voltage generator for receiving a coupling signal generated at the first common voltage from the coupling measuring unit and receiving the coupling signal at the first common voltage corresponding to the coupling signal, A first compensation circuit including a compensation section for inverting and amplifying the common voltage; And a second non-compensated reference signal which is inversely amplified by receiving a second polarity control signal and receiving a voltage that is distributed from the power distributor as a reference voltage and receives an output of the reference voltage, A second common voltage generating unit for receiving a coupling signal generated from the coupling measuring unit to generate a second common voltage and outputting a second signal corresponding to the coupling signal, And a second compensating circuit including a compensating unit for inverting and amplifying the common voltage And a common voltage compensation circuit. The method according to claim 1, Wherein the first and second polarity control signals are polar inversions every one vertical period and have polarities opposite to each other. The method according to claim 1, The coupling measurement unit measures a coupling signal of the first and second common voltages in the first and second dummy common lines formed at the upper end of the panel or the first and second dummy common lines formed at the lower end of the panel A common voltage compensation circuit. The method of claim 3, And a wiring for measuring the coupling signal is electrically connected to a gate PCB formed on the left side of the panel to feedback the measured coupling signal. The method according to claim 1, Wherein the first and second common voltages compensated by the first and second common voltage compensation circuits are applied to various external connection positions connected to the common wiring formed on the panel. The method according to claim 1, Wherein the power distributing unit comprises a first resistor and a first variable resistor connected in series between a power supply voltage terminal and a ground. The method according to claim 1, Wherein the inverting amplifier comprises a first operational amplifier having an inverting input terminal, a noninverting input terminal and an output terminal, a first capacitor and a second variable resistor formed in parallel between the output terminal and the inverting input terminal of the first operational amplifier, And a second resistor connected to the inverting input terminal. 8. The method of claim 7, Wherein the first operational amplifier receives a voltage distributed from the power distributing unit to the non-inverting input terminal and receives the polarity control signal to the inverting input terminal. The method according to claim 1, Wherein the compensation unit comprises a second operational amplifier having an inverting input terminal, a noninverting input terminal and an output terminal, an analog buffer is formed at an output terminal of the second operational amplifier, and an output of the analog buffer and an inversion A third resistor formed in parallel between the input terminal and the third resistor, a fourth resistor connected to the inverting input terminal, a third resistor connected to the non-inverting input terminal, And a fifth resistor is formed between the front ends of the fourth resistors. 10. The method of claim 9, Wherein the second operational amplifier receives the output of the inverting amplifier unit as the reference voltage and inputs the coupling signal measured by the coupling measuring unit to the inverting input terminal of the second operational amplifier. 10. The method of claim 9, Wherein the analog buffer comprises first and second transistors each having an output connected to a power supply voltage terminal and a ground, the output of the second operational amplifier being a signal of a common base terminal and being formed in series. A first and a second compensating circuits each composed of a power distributing unit, an inverting amplifying unit, and a compensating unit, and a coupling measuring unit. In the panel in which the data signal and the first and second common voltages of opposite polarities are applied, A common voltage compensation method of a common voltage compensation circuit for compensating a coupling signal induced in a common wiring in accordance with an inversion, Measuring a coupling signal of the first and second common voltages through the coupling measurement unit in the panel; Dividing the power supply voltage in each of the power distributing units of the first and second compensating circuits, and inputting the divided power voltage as a reference voltage to the respective inverting amplifying units; Receiving first and second polarity control signals from the respective inverting amplifying units and outputting first and second non-compensated reference signals inverted and amplified by feedback of the output; The first and second non-compensated reference signals are received as reference voltages and the outputs are fed back, and the coupling signals of the first and second common voltages are respectively received from the coupling measurement unit, Correspondingly inverting and amplifying the first and second common voltages to compensate for the first and second common voltages; Applying the compensated first and second common voltages to a plurality of external connection positions connected to a common wiring formed on the panel / RTI > 13. The method of claim 12, Wherein the first and second polarity control signals are polar inversions every one vertical period and are polar inverses of each other. 13. The method of claim 12, Wherein the coupling measurement unit measures the coupling signal in the first and second dummy common lines formed at the top of the panel or in the first and second dummy common lines formed at the bottom of the panel. 15. The method of claim 14, Wherein the coupling signal is electrically connected to a gate PCB formed on the left side of the panel, and the feedback signal is fed back to the compensating unit of the compensating circuit. A thin film transistor serving as a switching element is formed at an intersection of the gate and the data line, and the thin film transistor is connected in parallel with the thin film transistor, And a plurality of common wirings formed in a direction parallel to the gate wirings and in which first and second common voltages are alternately applied; The coupling signal generated in the first and second common voltages according to the polarity inversion of the data signal transmitted through the data line in the panel is supplied to the first and second dummy common lines formed on the upper portion of the panel, A power dividing section for dividing the power supply voltage, a voltage dividing section for dividing the power supplied to the power dividing section, An inverting amplifier for receiving a polarity control signal and outputting a non-compensated reference signal inverted and amplified; an output of the inverting amplifier for receiving a reference voltage; And a compensation unit for receiving the input signal and inverting and amplifying the input signal in response to the coupling signal, And the liquid crystal display device. 17. The method of claim 16, Wherein the polarity control signals input to the first and second compensation circuits are first and second polarity control signals that are polarity inversions every one vertical period and are opposite in polarity to each other. 17. The method of claim 16, And the coupling signals input to the first and second compensation circuits are coupling signals generated in the first and second common voltages, respectively.

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